Study on Spatial Temporal Distribution Characteristics of Air Quality Index in Beijing and Its Correlation with Local Meteorological Conditions

Table 1

The categories of AQI.

Air quality index range	Air quality level	Air quality index category	Represent color
0∼50	Level one	Excellent	Green
50∼100	Level two	Good	Yellow
100∼150	Level three	Mild pollution	Orange
150∼200	Level four	Moderate pollution	Red
200∼300	Level five	Heavy pollution	Purple
>300	Level six	Severe pollution	Maroon